Ferruginous Hawk Buteo regalis

Aves — Falconiformes — Accipitridae

CONSERVATION STATUS / CLASSIFICATION Rangewide: Apparently secure (G4) Statewide: Vulnerable breeding (S3B) ESA: No status USFS: Region 1: No status; Region 4: No status BLM: Regional/State imperiled (Type 3) IDFG: Protected nongame

BASIS FOR INCLUSION Population declines and threats.

TAXONOMY No subspecies is recognized (Bechard and Schmutz 1995).

DISTRIBUTION AND ABUNDANCE The ferruginous hawk breeds generally throughout western North America from southernmost Canada between the Great Plains and Rocky Mountains south to northern Arizona and New Mexico. Being an open–country species that inhabits grasslands, shrubsteppes, and deserts, this species is absent from most of northern and northeastern Idaho (Bechard et al. 1986, Bechard and Schmutz 1995). Distributed throughout southern Idaho, especially in shrubsteppe communities at the periphery of western piñon–juniper woodlands, the ferruginous hawk is primarily found in the Snake River plain (Groves et al. 1997a). A relatively uncommon species, it is estimated that there are approximately 625 breeding individuals in Idaho (Rosenberg 2004). Mostly absent from Idaho during the non–breeding season, the ferruginous hawk winters from northern California, western and southern Nevada, southwestern and northeastern Utah, extreme southern Wyoming, southwestern Nebraska, western and central Kansas and central Oklahoma, south through east–central Texas and Mexico to Baja California Norte, northern Sonora, Durango, and Coahuila (Bechard and Schmutz 1995).

POPULATION TREND Breeding Bird Survey (BBS) data indicate negative population trends (although none is statistically significant) for the ferruginous hawk in Idaho for the long–term period 1966– 2004 (–2.7% per year) and the more recent short–term period 1980–2004 (–11.8% per year) (Sauer et al. 2005). Across the species’ larger range, such as at the level of the western BBS region or the U.S. as a whole, population trends are more stable to increasing, although again, none are statistically significant.

HABITAT AND ECOLOGY The ferruginous hawk inhabits flat and rolling terrain in grassland or shrubsteppe regions, typically avoiding high elevation, forest interior, and narrow canyons (Bechard and Schmutz 1995). Occurs in grasslands, sagebrush country, saltbrush–greasewood shrublands, and the periphery of pinyon–juniper and other forests (Olendorff 1993). In Idaho, becomes locally abundant at the interface between piñon–juniper and shrubsteppe environments (Powers et al. 1975). This species hunts from the air or perch, most frequently near sunrise or sunset. Nests in trees or on cliffs with up to 8–10 nests per 100 km2 (39 mi2) if conditions are favorable (Groves et al. 1997). Breeding males in Idaho were estimated to have an average home range of 7–8 km2 (2.7–3.0 mi2; Bechard et al. 1986). In Idaho, the ferruginous hawk is associated with nesting Swainson’s hawks (Buteo swainsoni), commonly migrates southward in the fall, but resides year–round in limited numbers in the extreme southern part of the state (Groves et al. 1997a).

ISSUES Main issue threatening the ferruginous hawk appears to be agricultural development and cultivation of native grasslands (Olendorff 1993, Groves et al. 1997a). Population declines have been attributed to the deleterious effects of cultivation, grazing, poisoning and controlling small mammals, mining, and fire in nesting habitats (Olendorff 1993). A more recent concern is the development of wind farms, such as those in southern Idaho, where hawks could potentially collide with turbines during spring and fall migration movements (Erickson et al. 2001).

RECOMMENDED ACTIONS Primary conservation actions focused on maintaining or increasing current population numbers in Idaho should include enhancing nest substrates, maintaining prey populations (ground squirrels, etc.), and mitigating development impacts from wind farm turbines, mining, pipeline construction, and urbanization (Bechard and Schmutz 1995). Better data on mortality rates of migrating ferruginous hawks (and other raptors) as a result of wind farm development are needed.

Ferruginous Hawk Buteo regalis

Ecological Section

Predicted Breeding Distribution

Point Locations

Map created on September 22, 2005 and prepared by Idaho Conservation Data Center. Sources: Point data are from Idaho Conservation Data Center, Idaho Department of Fish and Game (2005). Predicted distribution is from the Wildlife Habitat Relationships Models (WHR), 0 20 40 80 Kilometers A Gap Analysis of Idaho: Final Report. Idaho Cooperative Fish and Wildlife Research Unit, Moscow, ID (Scott et al. 2002). Predicted distribution is approximate (for more information, go to http://www.wildlife.uidaho.edu/idgap/idgap_report.asp). 0 20 40 80 Miles